You'll never be left in the dark with the Orion 20mm Illuminated Centering Telescope Eyepiece. Whether you're acquiring and centering stars for GoTo system alignment, lining up guide stars and/or target objects for astrophotography, or just testing the accuracy of your tracking system, the 20mm Illuminated Centering Telescope Eyepiece will quickly become one of your most trusted and useful imaging tools.

In comparison to most standard low-focal length illuminated reticle telescope eyepieces, the 20mm Illuminated Centering Telescope Eyepiece offers a relatively long 20mm focal length and a wide 70-degree apparent field-of-view, making it easier to locate desirable targets for alignment or guiding. This virtually eliminates the need for swapping out high-power illuminated reticles with lower power eyepieces in order to center objects.

The Illuminated Centering Eyepiece is fully multi-coated (all air-to-glass surfaces) with anti-reflection coatings for bright, crisp views. It features a great 16mm eye relief and the barrel is threaded for Orion 1.25" filters. The illuminator switch doubles as a "dimmer" allowing you to adjust cross-hair brightness to the desired level.

Limited Warranty against defects in materials or workmanship for one year from date of purchase. This warranty is for the benefit of the original retail purchaser only. For complete warranty details contact us at 800-676-1343.

Design

Different eyepiece designs allow for a wide range of features, depending on the needs of the observer. Orthoscopic and Plossl designs can provide a great quality image with a standard field of view, but may be difficult to use at higher powers while wearing glasses due to the short eye-relief. Long eye-relief designs have more elements and can be more expensive, but work very well with glasses, even at higher powers. Wide angle designs provide a larger view of the sky at the same power as a standard eyepiece. More complex designs can combine all these attributes together in a single eyepiece.

Apparent field of view

The edge-to-edge angular diameter of the image displayed in a binocular as seen by the eyes of the observer. It is an inherent specification for a given binocular design. The "angular diameter" of an object is defined as the angle an object makes (subtends) as seen by an observer.

Eye relief

The distance, measured in millimeters, between the observer's eye and the eyepiece lens in which the entire field of view remains visible. Eye relief varies with the optical design but generally increases with decreasing magnification. Long eye relief is advantageous for observers who wear glasses, as they don't have to put their eye directly on the eyepiece to see the entire field of view, nor do they have to remove their eyewear.

Coatings

Binocular lenses and prisms are often coated with anti-reflective material to minimize light loss as light travels through the multiple optical surfaces of a typical binocular. Coatings help maximize the amount of light transmitted through each glass surface of a binocular, so as much light as possible reaches the observer's eyes to provide a bright and sharp image.

Good lenses are at least "fully coated," with a single layer of magnesium fluoride coating applied to each air-to-glass lens surface. Multiple layers of coatings are even more effective; the term "multi-coated" means one or more air-to-glass lens surface has multiple coatings. "Fully multi-coated" optics are even better, meaning all lens surfaces have multiple layers of anti-reflective coatings applied for maximum light transmission and optimal image quality.

Parfocal

Field stop diameter

The field stop is a mechanical ring in the eyepiece which provides the sharp edge to the field of view when looking through the eyepiece. The field stop diameter greatly affects the apparent field of view of the eyepiece; the larger the field stop diameter, the larger the apparent field of view is.

Barrel security recess

The barrel security recess is a shallow groove or depression cut into the 1.25" or 2" barrel of the eyepiece. In the event the thumb screw holding the eyepiece in the focuser becomes slightly loose, the eyepiece will not fall out because the tip of the thumb screw will catch on the lip of the security groove.

Warranty

This warranty gives you specific legal rights. It is not intended to remove or restrict your other legal rights under applicable local consumer law; your state or national statutory consumer rights governing the sale of consumer goods remain fully applicable.

Orders received by 1pm Eastern Time for in-stock items ship the same business day. Orders received after 1pm will ship the next business day. When an item is not in-stock we will ship it as soon as it becomes available. Typically in-stock items will ship first and backordered items will follow as soon as they are available. You have the option in check out to request that your order ship complete, if you'd prefer.

For photographing and guiding at the same time, the Orion Deluxe Off-Axis Guider is perfect. It eliminates the need for a separate guide scope, fixes tracking problems such as differential flexure and mirror shift, and reduces set up time.

For cleaning the lenses in your telescope or binocular, the Orion Microfiber Optics Cleaning Cloth lifts dirt, fingerprints, water and oil from surface without scratching, streaking or smearing delicate lens surfaces. The cloth is machine washable.

At Orion, we are committed to sharing our knowledge and passion for astronomy and astrophotography with the amateur astronomy community. Visit the Orion Community Center for in-depth information on telescopes, binoculars, and astrophotography. You can find astrophotography "how to" tips and share your best astronomy pictures here. Submit astronomy articles, events, and reviews, and even become a featured Orion customer!